Low carbon footprint expansive composition and methods of making and using same

ABSTRACT

Disclosed herein is a composition comprising a cementitious material, a pozzolanic material, aplite, and an aqueous fluid. Also disclosed herein is a method of servicing a wellbore penetrating a subterranean formation, comprising: placing the composition into the wellbore; and allowing the composition to form a set cement. The composition can develop suitable mechanical properties and permeability after setting in a wellbore and be expansive.

FIELD

This application relates to a composition, and more specifically thisapplication relates to a composition that can be used in the recovery ofnatural resources from a wellbore penetrating a subterranean formation.

BACKGROUND

This disclosure relates generally to a composition. More specifically,it relates to a composition and methods of making and using same fortreating a wellbore penetrating a subterranean formation, for exampleduring a cementing operation.

Natural resources such as gas, oil, and water residing in a subterraneanformation are usually recovered by drilling a wellbore down to thesubterranean formation while circulating a drilling fluid, also referredto as drilling mud, in the wellbore. After terminating circulation ofthe drilling fluid, a string of pipe, e.g., casing, is run in thewellbore. The drilling fluid is then usually circulated downward throughthe interior of the pipe and upward through the annulus, which islocated between the exterior of the pipe and the walls of the wellbore.Next, primary cementing is typically performed whereby a cement slurryis placed in the annulus and permitted to set into a hard mass (i.e.,sheath) to thereby attach the string of pipe to the walls of thewellbore and seal the annulus. Subsequent secondary cementing operationsmay also be performed. One example of a secondary cementing operation issqueeze cementing whereby a cement slurry is employed to plug and sealoff undesirable flow passages in the cement sheath and/or the casing.

While cement slurries have been developed heretofore, challengescontinue to exist with the successful use of cement slurries insubterranean cementing operations. The manufacture of cement is a veryenergy-intensive industry. Much of this energy is producing by burningfossil fuels such as coal, contributing to the production of “greenhousegases.” One of the most discussed of these greenhouse gases is carbondioxide (CO₂). The effect certain activities have on the climate interms of the total amount of greenhouse gases produced is oftendescribed as a “carbon footprint.” In addition, volumetric shrinkageduring hydration process of a cement slurry can lead to poor zonalisolation through the formation of micro-annuli and reduced shear bondstrength between the casing and cement. The resulting micro-annulirepresent flow channels which offer communication possibilities withinthe annulus, especially for gases. Relatively low permeability (e.g.,less than 5 micro Darcy) of a set cement barrier is also a designcriterion. Therefore, an ongoing need exists for an expansive cementslurry that has low carbon footprint and permeability.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1 illustrates surface equipment that can be used in the placementof a composition in accordance with some embodiments of the disclosure.

FIG. 2 is a depiction of the placement of a composition into asubterranean formation in accordance with some embodiments of thedisclosure.

FIG. 3A is a bar chart comparing crush strength of some samples inaccordance with some embodiments of the disclosure with and withoutaccelerator.

FIG. 3B is a bar chart comparing thickening time of some samples inaccordance with some embodiments of the disclosure with and withoutaccelerator.

FIG. 3C is a bar chart comparing the 28-day permeability of some samplesin accordance with some embodiments of the disclosure.

FIG. 3D is a graph showing results of ring expansion test as function oftime of some samples in accordance with some embodiments of thedisclosure.

FIG. 3E is a graph of hydration shrinkage of a standard class G basedcement in a volumetric shrinkage test setup.

FIGS. 4A-4E are bar charts comparing 7-day curing at 20° C./68° F.mechanical properties of some samples in accordance with someembodiments of the disclosure. The mechanical properties includeunconfined compressive strength, tensile strength, Young's Modulus ofelasticity, and the ratios of tensile strength/Young's modulus, andunconfined compressive strength/Young's Modulus.

FIGS. 5A-5B are bar charts comparing 24-hour crush compressive strengthof some samples in accordance with some embodiments of the disclosurewith and without accelerator. FIG. 5A represents curing at 40° C./104°F. and FIG. 5B represents curing at 80° C./176° F.

FIG. 5C is a bar chart comparing 28-day permeability of some samples inaccordance with some embodiments of the disclosure.

FIGS. 5D-5E are graphs presenting ring expansion test results of somesamples in accordance with some embodiments of the disclosure.

FIG. 5F is a graph of long-term ring expansion test results of a samplein accordance with some embodiments of the disclosure.

FIGS. 6A-6E are bar charts comparing 7-day curing at 80° C./176° F. and150° C./302° F. mechanical properties of some samples in accordance withsome embodiments of the disclosure. The mechanical properties includeunconfined compressive strength, tensile strength, Young's Modulus ofelasticity, and the ratios of tensile strength/Young's modulus, andunconfined compressive strength/Young's Modulus.

FIG. 7 is a bar chart comparing the estimated yield corrected (per m³cement slurry) carbon footprint of some samples in accordance with someembodiments of the disclosure.

FIG. 8 is an ultrasonic cement analyzer (UCA) chart of a class G cementbased sample.

FIG. 9A-9B are UCA charts of a sample at 150° C./302° F. and 180°C./356° F. in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

It is to be understood that “subterranean formation” encompasses bothareas below exposed earth and areas below earth covered by water such asocean or fresh water. Herein in the disclosure, “top” means the well atthe surface (e.g., at the wellhead which may be located on dry land orbelow water, e.g., a subsea wellhead), and the direction along awellbore towards the well surface is referred to as “up”, “bottom” meansthe end of the wellbore away from the surface, and the direction along awellbore away from the wellbore surface is referred to as “down.” Forexample, in a horizontal wellbore, two locations may be at the samelevel (i.e., depth within a subterranean formation), the location closerto the well surface (by comparing the lengths along the wellbore fromthe wellbore surface to the locations) is referred to as “above” theother location, the location farther away from the well surface (bycomparing the lengths along the wellbore from the wellbore surface tothe locations) is referred to as “below” or “lower than” the otherlocation.

Disclosed herein is a composition comprising a cementitious material, apozzolanic material, aplite, and an aqueous fluid. Herein a“cementitious material” refers to a settable material that makes up aconcrete mixture. In embodiments, the cementitious material comprises aPortland cement. Portland cements that are suited for use in thedisclosed composition include, but are not limited to, API Class A, C,G, H, low sulfate resistant cements, medium sulfate resistant cements,high sulfate resistant cements, other construction cements, orcombinations thereof. The API class A, C, G, and H cements areclassified according to API Specification 10. Additional examples ofPortland cements suitable for use in the present disclose include,without limitation, those classified as ASTM Type I, II, III, IV, or V.In embodiments, the cementitious material comprises a class C cement. Inembodiments, the cementitious material comprises a class G cement.

The cementitious material can be present in the composition in an amountof from about 1 weight percent by weight of blend (% BWOB) to about 90%BWOB based on the total weight of a cement blend comprising thecementitious material, the pozzolanic material, and the aplite.Alternatively, the cementitious material can be present in thecomposition in an amount of from about 10% BWOB to about 80% BWOB,alternatively from about 20% BWOB to about 70% BWOB, alternatively fromabout 30% BWOB to about 60% BWOB, or alternatively from about 40% BWOBto about 50% BWOB.

The pozzolanic material can comprise a material selected from the groupconsisting of Trass flour, recycled glass, fly ash, bottom ash,cenospheres, glass bubbles, slag, clays, calcined clays, partiallycalcined clays, kaolinite clays, lateritic clays, illite clays,crystalline silica, silica flour, cement kiln dust, volcanic rock,natural pozzolans, mine tailings, diatomaceous earth, zeolite, shale,ground vitrified pipe, agricultural waste ash, ground granulated blastfurnace slag, bentonite, pumice, and any combination thereof.

In embodiments, the pozzolanic material comprises Trass flour. The Trassflour is from Trass, which is the name of a volcanic tuff. Trass is agrey or cream-colored fragmental rock, largely composed of pumiceousdust, and may be regarded as a trachytic tuff. Trass can have similaringredients as Italian pozzolana. In embodiments, the Trass flour has ad50 particle size distribution of equal to or less than about 50microns, alternatively equal to or less than about 25 microns,alternatively equal to or less than about 15 microns, alternativelyequal to or less than about 5 microns, alternatively equal to or lessthan about 1 micron, or alternatively equal to or less than about 0.1micron.

In some embodiments, the pozzolanic material comprises pumice. Pumice isa type of extrusive volcanic rock, produced when lava with water andgases is discharged from a volcano. In other embodiments, the pozzolanicmaterial comprises calcined clay, which can be formed by heating clay athigh temperatures (e.g., equal to or greater than 1200° F.). In otherembodiments, the pozzolanic material comprises ground granulated blastfurnace slag, which can be produced by quenching molten iron slag from ablast furnace in water or steam, to produce product that is then driedand ground into a fine powder. In other embodiments, the pozzolanicmaterial comprises fly ash, which can be a byproduct of coal-firedelectric generating plants. In some embodiments, the pozzolanic materialcomprises bentonite.

The pozzolanic material can be present in the composition in an amountof from about 1% BWOB to about 90% BWOB based on the total weight of thecement blend. Alternatively, the pozzolanic material can be present inthe composition in an amount of from about 5% BWOB to about 80% BWOB,alternatively from about 10% BWOB to about 70% BWOB, alternatively fromabout 10% BWOB to about 60% BWOB, alternatively from about 15% BWOB toabout 50% BWOB, or alternatively from about 15% BWOB to about 35% BWOB.

In some embodiments, the aplite comprises granite. The granite can be ina form of granite powder. Aplite refers to any intrusive igneous rock ofsimple composition, such as granite, composed only of alkali feldspar,muscovite mica, and quartz; in a more restricted sense, uniformlyfine-grained (e.g., less than 2 millimetres [0.08 inch]),light-coloured, intrusive igneous rocks that have a characteristicgranular texture. The aplite can be present in the composition in anamount of from about 1% BWOB to about 90% BWOB based on the total weightof the cement blend. Alternatively, the aplite can be present in thecomposition in an amount of from about 5% BWOB to about 80% BWOB,alternatively from about 10% BWOB to about 70% BWOB, alternatively fromabout 10% BWOB to about 60% BWOB, alternatively from about 15% BWOB toabout 50% BWOB, or alternatively from about 15% BWOB to about 35% BWOB.

The composition can comprise an aqueous fluid. Generally, the aqueousfluid may be from any source, provided that it does not contain anamount of components that may undesirably affect the other components inthe composition. For example, the aqueous fluid can be selected from agroup consisting essentially of fresh water, surface water, groundwater, produced water, sea water, salt water, brine (e.g., undergroundnatural brine, formulated brine, etc.), and combinations thereof. Aformulated brine may be produced by dissolving one or more soluble saltsin water, a natural brine, or sea water. Representative soluble saltsinclude the chloride, bromide, acetate, and formate salts of potassium,sodium, calcium, magnesium, and zinc. The aqueous fluid can be presentin the composition in an amount effective to provide a slurry havingdesired (e.g., job or service specific) rheological properties. Inembodiments, the aqueous fluid is present in the composition in anamount effective to form a pumpable slurry of the composition.

In some embodiments, the composition further comprises silica fume. Insome embodiments, the silica fume is a component of the cement blend,and the cement blend comprises the cementitious material, the pozzolanicmaterial, the aplite, and the silica fume. The silica fume can bepresent in the composition in an amount of from about 0.5% BWOB to about50% BWOB based on the total weight of the cement blend. Alternatively,the silica fume can be present in the composition in an amount of fromabout 0.5% BWOB to about 40% BWOB, alternatively from about 1% BWOB toabout 30% BWOB, alternatively from about 1% BWOB to about 20% BWOB, oralternatively from about 1% BWOB to about 10% BWOB. The silica fume canalso be included in the composition in the form of a liquid, in suchembodiments the silica fume is added to a fluid (e.g., the liquid phase)of the composition instead of being a part of the cement blend. In someembodiments, the silica fume is in forms of both a solid and a liquid,and is added to the cement blend and the fluid, respectively.

In some embodiments, the composition comprises the cementitiousmaterial, the pozzolanic material, aplite, the silica fume, and theaqueous fluid, wherein the pozzolanic material comprises Trass flour andthe aplite comprises granite. In some embodiments, the compositioncomprises the cementitious material, the pozzolanic material, aplite,the silica fume, and the aqueous fluid, wherein the cementitiousmaterial comprises a Portland cement, the pozzolanic material comprisesTrass flour, and the aplite comprises granite.

In embodiments, the composition further comprises a sodium chloride andsodium sulfate blend. The sodium chloride and sodium sulfate blend canoperate as an accelerator. The sodium chloride can be present in thecomposition in an amount ranging from about 0.01% BWOB to about 10% BWOBbased on the total weight of the cement blend. Alternatively, the sodiumchloride can be present in the composition in an amount of from about0.01% BWOB to about 8% BWOB, alternatively from about 0.1% BWOB to about6% BWOB, alternatively from about 0.1% BWOB to about 5% BWOB, oralternatively from about 0.1% BWOB to about 1% BWOB. The sodium sulfatecan be present in the composition in an amount ranging from about 0.01%BWOB to about 10% BWOB based on the total weight of the cement blend.Alternatively, the sodium sulfate can be present in the composition inan amount of from about 0.01% BWOB to about 8% BWOB, alternatively fromabout 0.1% BWOB to about 6% BWOB, alternatively from about 0.1% BWOB toabout 5% BWOB, or alternatively from about 0.1% BWOB to about 1% BWOB.In embodiments, a molar ratio of sodium chloride to sodium sulfate inthe composition is in a range of from about 1:10 to about 10:1,alternatively from about 1:5 to about 5:1, or alternatively from about1:2 to about 2:1. In some embodiments, the sodium chloride and sodiumsulfate blend can be added in the form of a liquid.

In some embodiments, the composition excludes an expansion additive. Inother embodiments the composition includes an expansion additive. Forexample, an expansion additive can be present in the composition in anamount of equal to or less than about 10% BWOB based on the total weightof the cement blend, alternatively equal to or less than about 5% BWOB,alternatively from about 0.5% BWOB to about 4% BWOB, or alternativelyequal to or less than about 0.001% BWOB.

In embodiments, the composition further comprises a pre-blendedstabilizing agent. The pre-blended stabilizing agent can comprisebentonite, sepiolite, attapulgite, water swellable synthetic clays,Diutan gum, xanthan gum, wellan gum, guar gum, modified guar gum,hydroxy ethyl cellulose, modified cellulose, other classes ofpolysaccharides, or combinations thereof. In embodiments, thepre-blended stabilizing agent is prepared before making the composition.The pre-blended stabilizing agent can be present in the composition inan amount ranging from about 0.01% BWOB to about 10% BWOB based on thetotal weight of the cement blend, alternatively from about 0.05% BWOB toabout 6% BWOB, or alternatively from about 0.1% BWOB to about 3% BWOB.The stabilizing agent can be added in a form of liquid or powder.

In some embodiments, the composition further comprises limestone. Insuch embodiments, the limestone is a component of the cement blend.Limestone is a type of carbonate sedimentary rock. Limestone can becomposed mostly of minerals calcite and aragonite, which are differentcrystal forms of calcium carbonate. In embodiments, limestone is presentin the composition in an amount ranging from about 0.01% BWOB to about90% BWOB based on the total weight of the cement blend, alternativelyfrom about 0.05% BWOB to about 50% BWOB, or alternatively from about0.1% BWOB to about 30% BWOB.

In embodiments, the composition further comprises one or more additives.The one or more additives can comprise weighting agents, retarders,accelerators, activators, gas migration control additives, lightweightadditives, gas-generating additives, mechanical-property-enhancingadditives (e.g., carbon fibers, glass fibers, metal fibers, mineralsfibers, polymeric elastomers, latexes, etc.), lost-circulationmaterials, filtration-control additives, fluid-loss-control additives,defoaming agents, foaming agents, transition time modifiers,dispersants, thixotropic additives, suspending agents, or combinationsthereof. One having ordinary skill in the art, with the benefit of thisdisclosure, should be able to select one or more appropriate additivesfor a particular application. The one or more additives can be presentin the composition in an amount ranging from about 0.01% BWOB to about50% BWOB based on the total weight of the cement blend, alternativelyfrom about 0.05% BWOB to about 40% BWOB, alternatively from about 0.1%BWOB to about 30% BWOB, alternatively from about 1% BWOB to about 20%BWOB, or alternatively from about 1% BWOB to about 10% BWOB.

The composition disclosed herein can have any suitable density,including, but not limited to, in a range of from about 500 kg/m³ toabout 3,000 kg/m³, alternatively from about 800 km/m³ to about 2,800kg/m³, alternatively from about 1,200 kg/m³ to about 2,800 kg/m³,alternatively from about 1,200 kg/m³ to about 2,600 kg/m³, oralternatively from about 1,300 kg/m³ to about 2,100 kg/m³.

The composition can have a positive 7-day circumferential change indimension in a range of from about 0.01% to about 2% at from about 20°C./68° F. to about 150° C./302° F., alternatively from about 0.05% toabout 1%, alternatively from about 0.05% to about 0.8%, alternativelyfrom about 0.05% to about 0.4%, or alternatively from about 0.05% toabout 0.2%, when measured in a ring expansion test in accordance withtest standard API 10B-5 on Determination of shrinkage or expansion underconditions of free access of water at atmospheric pressure—Anmlar ringtest. The time is 7 days after mixing the cement blend with the aqueousfluid.

The composition can have a positive 14-day circumferential change indimension in a range of from about 0.01% to about 2% at from about 20°C./68° F. to about 150° C./302° F., alternatively from about 0.05% toabout 1%, alternatively from about 0.05% to about 0.8%, alternativelyfrom about 0.05% to about 0.4%, or alternatively from about 0.05% toabout 0.2%, when measured in a ring expansion test in accordance withtest standard API 10B-5. The time is 14 days after mixing the cementblend with the aqueous fluid. The expansion (e.g., a positive 7-daycircumferential change, 14-day circumferential change) can be increasedby including a standard expansion material (e.g., an expansion additive)in the composition when a higher expansion is desired.

In embodiments, the composition has a thickening time. The thickeningtime herein can refer to the time required for the composition toachieve 50. Bearden units of Consistency (Bc) after preparation of thecomposition. At about 50 Bc, the composition undergoes a conversion froma pumpable fluid state to a non-pumpable gel. The thickening time can bean important design factor as the composition may be pumped thousands ofmeters through conduit and may take hours to place. Other values can beused to define the thickening time too, such as 30, 40, 70 or 100 Bc. Inorder to keep the composition in a pumpable state for an appropriateamount of time, additives such as retarders and accelerators can beadded to modulate the pump time by shortening or extending thethickening time. A measurement of Bearden units of Consistency (Bc) canbe considered a thickening time test which is performed on a movingfluid. In a thickening time test, an apparatus including a pressurizedconsistometer can apply temperature and pressure to a slurry (e.g., acomposition) while the slurry is being stirred by a paddle. A resistorarm and potentiometer coupled to the paddle can provide an output inunits of Bearden units of consistency.

In embodiments, the composition has a thickening time to reach about 50Bc in a range of from about 2.0 hours to about 20.0 hours at about 50°F., alternatively from about 2.0 hours to about 18.0 hours,alternatively from about 2.0 hours to about 15.0 hours, alternativelyfrom about 3.0 hours to about 10.0 hours, when measured in accordancewith test standard API-RP-10B-2.

In embodiments, the composition has a thickening time to reach about 50Bc in a range of from about 2.0 hours to about 20.0 hours at about 68°F., alternatively from about 3.0 hours to about 18.0 hours,alternatively from about 3.0 hours to about 14.0 hours, alternativelyfrom about 3.0 hours to about 9.0 hours, alternatively from about 3.0hours to about 8.0 hours, alternatively from about 3.0 hours to about7.0 hours, when measured in accordance with test standard API-RP-10B-2.

Compressive strength is generally the capacity of a material orstructure to withstand axially directed compression forces. Thecompressive strength of a composition can be measured at a specifiedtime (e.g., 24 hours) after a cement blend has been mixed with water andthe resultant cement slurry is maintained under specified temperatureand pressure conditions to form a hardened, set cement. For example,compressive strength can be measured at a time in the range of fromabout 12 to about 48 hours (or longer) after the cement slurry is mixed,and the cement slurry is maintained typically at a temperature of from0° C./32° F. to about 204° C./400° F. and a suitable pressure, duringwhich time the cement slurry can set into a hardened mass. Compressivestrength can be measured by either a destructive method ornon-destructive method. The destructive method physically tests thestrength of hardened samples at various points in time by crushing thesamples in a compression-testing machine. The compressive strength iscalculated from the failure load divided by the cross-sectional arearesisting the load and is reported in units of pound-force per squareinch (psi). Non-destructive methods can employ an ultrasonic cementanalyzer (UCA). A UCA can be available from Fann® Instrument Company,Houston, TX. Compressive strengths can be determined in accordance withAPI RP 10B-2, Recommended Practice for Testing Well Cements, FirstEdition, July 2005.

In embodiments, the composition has a time to reach 50 psi (345 kPa)compressive strength (also referred to as “time to reach 50 psi”)measured in an ultrasonic cement analyzer (UCA) test in accordance withtest standard API-RP-10B-2. The time to reach 50 psi under staticconditions in a UCA can be used as an estimation of the initial set timeof a composition. The time to reach 50 psi can be the time it takes fora cement slurry to transition from a pumpable fluid state to a hardenedset state.

In embodiments, the composition has a time to reach 50 psi compressivestrength in a range of from about 2.0 hours to about 24.0 hours at about20° C./68° F. to about 150° C./302° F. in a UCA test, alternatively fromabout 2.0 hours to about 20.0 hours, alternatively from about 2.0 hoursto about 18.0 hours, alternatively from about 3.0 hours to about 15.0hours, or alternatively from about 3.0 hours to about 10.0 hours, whenmeasured in accordance with test standard API-RP-10B-2.

In embodiments, the composition has a 24-hour compressive strength (alsoreferred to as “24-hour crush strength” or “24-hour crush compressivestrength”) measured in accordance with test standard API-RP-10B-2. The24-hour compressive strength can be in a range of from about 50 psi toabout 10,000 psi at from about 10° C./50° F. to about 80° C./176° F. ina UCA test, alternatively from about 100. psi to about 7,500 psi,alternatively from about 200. psi to about 5,500 psi, alternatively fromabout 250 psi to about 3,500 psi, alternatively from about 300 psi toabout 2,500 psi, or alternatively from about 300 psi to about 2,000 psi.The time is 24-hour period after mixing the cement blend with theaqueous fluid.

In embodiments, the composition has a 28-day compressive strength (alsoreferred to as “28-day crush strength” or “28-day crush compressivestrength”) measured in accordance with test standard API-RP-10B-2. The28-day compressive strength can be in a range of from about 50 psi toabout 10,000 psi at from about 80° C./176° F. to about 150° C./302° F.in a UCA test, alternatively from about 100 psi to about 10,000 psi,alternatively from about 200 psi to about 7,500 psi, alternatively fromabout 250 psi to about 5,500 psi, alternatively from about 300 psi toabout 3,500 psi, alternatively from about 300 psi to about 2,500 psi, oralternatively from about 300 psi to about 1,500 psi. The time is 28-dayperiod after mixing the cement blend with water.

The composition can have a stable or increasing compressive strength astime increases from about 1 week to about 6 weeks, at a temperaturebetween about 80° C./176° F. to about 180° C./356° F. in an ultrasoniccement analyzer (UCA) test when measured in accordance with teststandard API-RP-10B-2.

In embodiments, the composition has a 7-day unconfined compressivestrength (UCS) of from about 200 psi to about 5,000 psi at from about20° C./68° F. to about 150° C./302° F. when measured in accordance withtest standard ASTM D7012-14e1, alternatively from about 700 psi to about5,000 psi, alternatively from about 800 psi to about 4,000 psi,alternatively from about 800 psi to about 3,000 psi, or alternativelyfrom about 900 psi to about 3,000 psi. The unconfined compressivestrength, is the maximum stress that a set composition can endure whenconfining pressure is zero. It can be measured using a destructivemethod, where the maximum stress recorded at failure is the unconfinedcompressive strength, also referred to as the unconfined crush strengthor crush compressive strength. 7-day unconfined compressive strength canbe measured after 7 days from preparation of the composition.

In embodiments, the composition has a 7-day tensile strength (TS) offrom about 25 psi to about 1,000 psi at from about 20° C./68° F. toabout 150° C./302° F. when measured in accordance with test standardASTM D3967-16, alternatively from about 70 psi to about 750 psi,alternatively from about 100 psi to about 550 psi, alternatively fromabout 100 psi to about 500 psi, or alternatively from about 200 psi toabout 500 psi. Tensile strength is also referred to as Brazilian TensileStrength. Tensile strength is generally the capacity of a material towithstand loads tending to elongate, as opposed to compressive strength.The tensile strength of the composition may be measured at a specifiedtime (e.g., 7 days) after the cement blend has been mixed with water andthe resultant composition is maintained under specified temperature andpressure conditions. For example, tensile strength can be measured at 7days after the composition is mixed and the composition is maintained ata temperature of from 10° C./50° F. to about 204° C./200° F. and asuitable pressure. Tensile strength may be measured using any suitablemethod, including without limitation in accordance with the proceduredescribed in ASTM C307. That is, specimens may be prepared in briquettemolds having the appearance of dog biscuits with a one square inchcross-sectional area at the middle. Tension may then be applied at theenlarged ends of the specimens until the specimens break at the centerarea. The tension in pounds per square inch at which the specimen breaksis the tensile strength of the material tested.

In embodiments, the composition has a 7-day Young's modulus (YM) of fromabout 2 GPa to about 14 GPa at from about 20° C./68° F. to about 150°C./302° F., alternatively from about 3 GPa to about 10 GPa,alternatively from about 3 GPa to about 9 GPa, alternatively from about3 GPa to about 8 GPa, or alternatively from about 4 GPa to about 8 GPa.Young's modulus also referred to as the modulus of elasticity is ameasure of the relationship of an applied stress to the resultantstrain. In general, a highly deformable (plastic) material will exhibita lower modulus when the confined stress is increased. Thus, the Young'smodulus is an elastic constant that demonstrates the ability of thetested material to withstand applied loads. A number of differentlaboratory techniques may be used to measure the Young's modulus of atreatment fluid including the composition after the treatment fluid hasbeen allowed to set for a period of time at specified temperature andpressure conditions.

In embodiments, the composition has a ratio of the 7-day tensilestrength (TS) to the 7-day YM of from about 30 psi/GPa to about 75psi/GPa at from about 20° C./68° F. to about 150° C./302° F. whenmeasured in accordance with test standard ASTM D3967-16, alternativelyfrom about 30 psi/GPa to about 70 psi/GPa, alternatively from about 35psi/GPa to about 65 psi/GPa, or alternatively from about 35 psi/GPa toabout 60 psi/GPa.

In embodiments, the composition has a ratio of the 7-day unconfinedcompressive strength (UCS) to the 7-day YM of from about 200 psi/GPa toabout 500 psi/GPa at from about 68° F. to about 302° F. when measured inaccordance with test standard ASTM D7012-14e1, alternatively from about200 psi/GPa to about 480 psi/GPa, alternatively from about 240 psi/GPato about 480 psi/GPa, or alternatively from about 280 psi/GPa to about450 psi/GPa.

In embodiments, after setting, the composition has a permeabilitymeasured in a Hassler type core holder in accordance with test standardAPI-RP-10B-2. Permeability is a measure of the amount of water or othersubstances that can penetrate through the composition after setting. Theset composition can have a permeability equal to or less than about 30micro Darcy (μD), alternatively equal to or less than about 10 μD,alternatively equal to or less than about 6 μD, or alternatively equalto or less than about 5 μD.

28-day permeability is the permeability measured after 28 days frompreparation of the composition. In embodiments, the composition has a28-day permeability of equal to or less than about 30 μD (micro Darcy)at from about 20° C./68° F. to about 80° C./176° F. when measured in aHassler type core holder in accordance with test standard API-RP-10B-2,alternatively equal to or less than about 20 μD, alternatively equal toor less than about 10 μD, alternatively equal to or less than about 5μD, alternatively equal to or less than about 4 μD, alternatively equalto or less than about 3 μD, alternatively equal to or less than about 2μD, alternatively equal to or less than about 1 μD, or alternativelyequal to or less than about 0.1 μD.

In embodiments, the composition has a 28-day permeability of equal to orless than about 30 μD at from about 80° C./176° F. to about 150° C./302°F. when measured in a Hassler type core holder in accordance with teststandard API-RP-10B-2, alternatively equal to or less than about 10 μD,alternatively equal to or less than about 5 μD, alternatively equal toor less than about 3 μD, alternatively equal to or less than about 2 μD,alternatively equal to or less than about 1 μD, or alternatively equalto or less than about 0.1 μD.

In embodiments, the composition has a yield corrected carbon footprint,also referred to as yield corrected CO₂ footprint, of equal to or lessthan about 800 kilograms of equivalent CO₂ per cubic meter of thecomposition (kg/m³), alternatively equal to or less than about 750kg/m³, alternatively equal to or less than about 700 kg/m³,alternatively equal to or less than about 650 kg/m³, alternatively equalto or less than about 600 kg/m³, alternatively equal to or less thanabout 550 kg/m³, alternatively equal to or less than about 500 kg/m³, oralternatively equal to or less than about 450 kg/m³.

Carbon footprint, which refers to carbon emissions due to a material,can be determined by a cradle to grave lifecycle analysis of thematerial. Cradle to grave includes emissions related to production,transportation, storage, usage and disposal stages of a material. Totalemissions associated with a material is the sum of emissions in eachphase. Emissions can be expressed as kilograms of equivalent CO₂ perunit mass (or volume) of the material. There are several standards forcomputing the carbon emissions of a material. For example, the UnitedStates Environmental Protection Agency (EPA) publishes standards listedin the EPA's Waste Reduction Model (WARM) which allows for calculationof the carbon emissions of a material. Another source of standard is theCalifornia Air Resources Board's green house gas quantificationmethodology. The present disclosure uses data from certain suppliers ofeach component for calculating carbon footprint for materials. Whereavailable, Environmental Product Declarations (EPD) certificates havebeen used. In embodiments, a dry blend comprises the cement blend andother solid components of the composition. The carbon footprint of a dryblend is calculated using Equation (1) as below:Carbon footprint=Σ_(k=1)(carbon footprint)_(k) ·x _(k)  (1)wherein the dry blend comprises n components, wherein (carbonfootprint)_(k) is the carbon footprint of pure component k, and x_(k) isthe concentration of component k in the dry blend. The yield correctedcarbon footprint is an estimate of carbon footprint per volume pumpedfor a cement slurry (e.g., the composition). A yield value of an exampledesign of the composition can be used to calculate the consumption ofthe dry blend per given unit volume of the cement slurry (e.g., thecomposition) mixed to calculate the yield corrected carbon footprint.For example, if the yield value for a given composition (or a cementslurry) is 106 liter/100 kg, the corresponding blend requirement for 1m³ of the example composition will be 943 kg. Hence the yield correctionfactor for the composition's (or slurry's) CO₂ footprint is 0.943 versusthe dry blend's CO₂ footprint when contribution from any liquidadditives is ignored.

In some embodiments, the composition is capable to withstand atemperature in a range of from about 0° C./32° F. to about 204° C./400°F., alternatively from about 0° C./32° F. to about 191° C./375° F.,alternatively from about 0° C./32° F. to about 180° C./356° F.,alternatively from about 0° C./32° F. to about 163° C./325° F., oralternatively from about 0° C./32° F. to about 150° C./302° F.

A composition of the type disclosed herein can be prepared using anysuitable method. In embodiments, the method comprises mixing components(e.g., Portland cement, Trass flour, an aqueous fluid) of thecomposition using mixing equipment (e.g., a batch mixer, a jet mixer, are-circulating mixer, a blender, a mixing head of a solid feedingsystem). Mixing the components of the composition can comprise one ormore steps. For example, mixing the components of the composition cancomprise dry mixing components of the cement blend and optional othersolid components (e.g., a weighting agent) to form a dry blend, andmixing the dry blend with an aqueous fluid and optional other additivesto form a pumpable slurry (e.g., a homogeneous fluid). Any container(s)that is compatible with the components and has sufficient space can beused for mixing.

In embodiments, mixing the components of the composition can beon-the-fly (e.g., in real time or on-location). The composition can beused as a wellbore servicing fluid and be prepared at a wellsite. Forexample, the components of the cement blend (e.g., Portland cement,Trass flour) can be transported to the wellsite and combined (e.g.,mixed/blended) with an aqueous fluid located proximate the wellsite toform the composition. The aqueous fluid can be conveyed from a source tothe wellsite or be available at the wellsite prior to the combining. Thecement blend can be prepared at a location remote from the wellsite andtransported to the wellsite, and, if necessary, stored at the on-sitelocation. When it is desirable to prepare the composition at thewellsite, the components of the cement blend along with additionalaqueous fluid and optional other additives can be mixed to form amixture (e.g. in a blender tub, for example mounted on a trailer).Additives can be added to the composition during preparation thereof(e.g., during mixing) and/or on-the-fly (e.g., in real time oron-location) by addition to (e.g., injection into) the composition whenbeing pumped into the wellbore.

The method disclosed herein can further comprise introducing thecomposition into a subterranean formation, and allowing at least aportion of the composition to set. In embodiments, introducing thecomposition into the subterranean formation uses one or more pumps.

A composition of the type disclosed herein can be used as a cementitiousfluid. A cementitious fluid refers to a material that can set and beused to permanently seal an annular space between casing and a wellborewall. A cementitious fluid can also be used to seal formations toprevent loss of drilling fluid (e.g., in squeeze cementing operations)and for operations ranging from setting kick-off plugs to plug andabandonment of a wellbore. Generally, a cementitious fluid used in oilfield is pumpable in relatively narrow annulus over long distances.Disclosed herein is a method of servicing a wellbore penetrating asubterranean formation. In embodiments, the method comprises placing acomposition disclosed herein into the wellbore.

In embodiments, the composition is used in a subterranean workspace, forexample in cementing underground pipe such as sewer pipe or wellborecasing. In embodiments, the composition is employed in primary cementingof a wellbore for the recovery of natural resources such as water orhydrocarbons. Primary cementing first involves drilling a wellbore to adesired depth such that the wellbore penetrates a subterranean formationwhile circulating a drilling fluid through the wellbore. Subsequent todrilling the wellbore, at least one conduit such as a casing may beplaced in the wellbore while leaving a space known as the annulus (i.e.,annular space) between the wall of the conduit and the wall of thewellbore. The drilling fluid may then be displaced down through theconduit and up through the annulus one or more times, for example,twice, to clean out the hole. The composition can then be conveyed(e.g., pumped) downhole and up through the annulus, thereby displacingthe drilling fluid from the wellbore. In embodiments, the compositionsets into a hard mass, which forms a cement column that isolates anadjacent portion of the subterranean formation and provides support tothe adjacent conduit.

In some other embodiments, the composition is employed in a secondarycementing operation such as squeeze cementing, which is performed afterthe primary cementing operation. In squeeze cementing, the compositioncan be forced under pressure into permeable zones through which fluidcan undesirably migrate in the wellbore. Examples of such permeablezones include fissures, cracks, fractures, streaks, flow channels,voids, high permeability streaks, annular voids, or combinationsthereof. The permeable zones can be present in the cement columnresiding in the annulus, a wall of the conduit in the wellbore, a microannulus between the cement column and the subterranean formation, and/ora micro annulus between the cement column and the conduit. Thecomposition can set within the permeable zones, thereby forming a hardmass to plug those zones and prevent fluid from leaking therethrough.

An example primary cementing technique using a composition will now bedescribed with reference to FIGS. 1 and 2 . FIG. 1 illustrates surfaceequipment 200 that can be used in the placement of a composition inaccordance with certain examples. It will be noted that while FIG. 1generally depicts a land-based operation, the principles describedherein are equally applicable to subsea operations that employ floatingor sea-based platforms and rigs, without departing from the scope of thedisclosure. As illustrated by FIG. 1 , the surface equipment 200 caninclude a cementing unit 205, which can include one or more cementtrucks. The cementing unit 205 can include mixing equipment 210 andpumping equipment 210. Cementing unit 205, or multiple cementing units205, can pump a composition 14 of the type disclosed herein through afeed pipe 220 and to a cementing head 225 which conveys the composition14 downhole. Composition 14 can displace other fluids present in thewellbore, such as drilling fluids and spacer fluids, which can exit thewellbore through an annulus and flow through pipe 235 to mud pit 240.

Referring to FIG. 2 , the composition 14 can be placed into asubterranean formation 20 in accordance with example embodiments. Asillustrated, a wellbore 22 can be drilled into the subterraneanformation 20. While wellbore 22 is shown extending generally verticallyinto the subterranean formation 20, the principles described herein arealso applicable to wellbores that extend at an angle through thesubterranean formation 20, such as horizontal and slanted wellbores. Asillustrated, the wellbore 22 comprises walls 24 of the wellbore 22. Inthe illustrated embodiment, a surface casing 26 has been inserted intothe wellbore 22. The surface casing 26 can be cemented to the walls 24of the wellbore 22 by cement sheath 28. In the illustrated embodiment,one or more additional conduits (e.g., intermediate casing, productioncasing, liners, etc.), shown here as casing 30 can also be disposed inthe wellbore 22. As illustrated, there is a wellbore annulus (i.e.,annular space) 32 formed between the casing 30 and the walls 24 of thewellbore 22 and/or the surface casing 26. One or more centralizers 34can be attached to the casing 30, for example, to centralize the casing30 in the wellbore 22 prior to and during the cementing operation.

With continued reference to FIG. 2 , the composition 14 can be placed(e.g., pumped) down the interior of the casing 30. The composition 14can be allowed to flow down the interior of the casing 30 through thecasing shoe 42 at the bottom of the casing 30 and up around the casing30 into the wellbore annulus 32. The composition 14 can be allowed toset in the wellbore annulus 32, for example, to form a cement sheaththat supports and positions the casing 30 in the wellbore 22. Othertechniques can also be utilized for introduction of the composition 14.By way of example, reverse circulation techniques can be used thatincludes introducing the composition 14 into the subterranean formation20 by way of the wellbore annulus 32 instead of through the casing 30.In such embodiments, the method comprises circulating the composition 14down through the wellbore annulus 32 and back up through the interior ofthe casing 30.

In embodiments, the composition 14 displaces other fluids 36, such asdrilling fluids and/or spacer fluids that can be present in the interiorof the casing 30 and/or the wellbore annulus 32. At least a portion ofthe displaced fluids 36 can exit the wellbore annulus 32 via a flow lineand be deposited, for example, in one or more retention pits (e.g., amud pit 240 in FIG. 1 ). A bottom plug 44 can be introduced into thewellbore 22 ahead of the composition 14, for example, to separate thecomposition 14 from the fluids 36 that can be inside the casing 30 priorto cementing. After the bottom plug 44 reaches the landing collar 46, adiaphragm or other suitable device can rupture to allow the composition14 through the bottom plug 44. In FIG. 2 , the bottom plug 44 is shownon the landing collar 46. In the illustrated embodiment, a top plug 48can be introduced into the wellbore 22 behind the composition 14. Thetop plug 48 can separate the composition 14 from a displacement fluid 50and also push the composition 14 through the bottom plug 44.

In embodiments, the method disclosed herein further comprisescirculating the composition down through a conduit (e.g., casing) andback up through an annular space (also referred to as an annulus or awellbore annulus) between an outside wall of the conduit and a wall ofthe wellbore. In some other embodiments, the method disclosed hereinfurther comprises circulating the composition down through an annularspace between an outside wall of a conduit and a wall of the wellboreand back up through the conduit. The method can further compriseallowing the composition to form a set cement. In embodiments, the setcement has a positive expansion. In other words, the set cement does notshrink in volume. An expansion rate of the set cement can be from 0 toabout 10%, alternatively from 0 to about 5%, alternatively from 0 toabout 2%, alternatively from 0 to about 1%, or alternatively from 0 toabout 0.5%. In some embodiments, the set cement has a permeability offrom about 0.01 μD to about 30 μD, alternatively from about 0.01 μD toabout 10 μD, or alternatively from about 0.01 μD to about 6 μD.

Disclosed herein is a method of servicing a wellbore penetrating asubterranean formation. The method can comprise placing a composition ofthe type disclosed herein into the wellbore, and allowing at least aportion of the composition to set. Also disclosed herein is a method ofservicing a wellbore with a conduit (e.g., casing, production tubing,tubular, or other mechanical conveyance, etc.) disposed therein to forman annular space between a wellbore wall and an outer surface of theconduit. In embodiments, the method comprises placing a composition ofthe type disclosed herein into at least a portion of the annular space,and allowing at least a portion of the composition to set.

In the method disclosed herein, placing a composition into at least aportion of the annular space can be in different directions. In someembodiments, placing the composition comprises circulating thecomposition down through the conduit and back up through the annularspace. In some other embodiments, placing the composition comprisescirculating the composition down through the annular space and back upthrough the conduit. In embodiments, the conduit comprises casing.

Various benefits may be realized by utilization of the presentlydisclosed methods and compositions. The composition as disclosed hereincan develop suitable mechanical properties and permeability aftersetting and has a relatively low carbon footprint. The composition canalso be expansive and thus avoid forming flow channels after setting ofthe composition.

EXAMPLES

The embodiments having been generally described, the following examplesare given as particular embodiments of the disclosure and to demonstratethe practice and advantages thereof. It is understood that the examplesare given by way of illustration and are not intended to limit thespecification or the claims in any manner.

Example 1

Three cement blends were prepared according to compositions in Table 1.Two compositions were prepared per API procedures with each cement blendby mixing the cement blend with water, without and with accelerator(sodium sulfate and/or sodium chloride), and were named “Blend x(without accelerator)” and “Blend x (with accelerator)”, respectively,wherein x is the number of the cement blend. The wt. % is the weightpercentage of a component in a cement blend. The density of the sixcompositions were 1,600 kg/m³.

TABLE 1 Cement blend composition Blend 1 Blend 2 Blend 3 Cement WithoutWith Without With Without With blend Unit accelerator acceleratoraccelerator accelerator accelerator accelerator Cementitious wt. % 45 4545 45 45 45 material Aplite wt. % 15 15 25 25 35 35 Pozzolanic wt. % 3535 25 25 15 15 material Silica fume wt. % 5 5 5 5 5 5 Accelerator % BWOB1 1 1

12-to-24-hour compressive strength of Blend 2 (without accelerator andwith accelerator) were measured at different temperatures in accordancewith test standard API-RP-10B-2. Results in FIG. 3A shows that thecompressive strength increased as the temperature increased for the sameblend; Blend 2 (with accelerator) had greater compressive strength thanBlend 2 (without accelerator); for the same sample at the sametemperature, 24-hour compressive strength was greater than 12-hourcompressive strength; and for the same blend and temperature, thecomposition with accelerator had a greater 24-hour compressive strengththan without accelerator.

Thickening time of Blend 2 (without accelerator and with accelerator) atdifferent temperatures was measured in accordance with test standardAPI-RP-10B-2. Results in FIG. 3B shows that thickening time decreased asthe temperature increased, and Blend 2 (with accelerator) had a shorterthickening time than Blend 2 (without accelerator).

28-day permeability of Blend 2 (without accelerator and withaccelerator) and Blend 3 (without accelerator and with accelerator) at20° C./68° F. was measured in a Hassler type core holder in accordancewith test standard API-RP-10B-2. Results in FIG. 3C are in μD (microDarcy) and shows that all the samples had a 28-day permeability equal toor lower than 0.02 μD.

A ring expansion test was run for Blend 2 (without accelerator and withaccelerator). After running the test for given number of days, the ringmolds were measured and the percentage of expansion of each sample wascalculated according to the procedure and equations in API 10B-5 onDetermination of shrinkage or expansion under conditions of free accessof water at atmospheric pressure—Anmlar ring test. The temperature wasincreased from 20° C./68° F. to 80° C./176° F. on day 28 to acceleratethe reaction and determine the ultimate plateau. FIG. 3D shows ringexpansion test results for Blend 2 (without accelerator and withaccelerator) at 20° C./68° F. (0 to 28 days) and 80° C./176° F. (after28 days). After 7 days, the circumferential change was greater than0.05%; and after 42 days (14 days at 80° C./176° F.), thecircumferential change was greater than 0.15%. Blend 2 (withaccelerator) had equal to or greater circumferential change than Blend 2(without accelerator) at the same time.

FIG. 3E shows typical hydration shrinkage of a standard class G basedcement in a volumetric shrinkage test at 20° C./68° F. for comparison. Astandard class G based cement showed no expansion but shrinkage duringthe test.

Experiments and calculations were also performed to Blends 1-3 (withoutaccelerator and with accelerator) for 7-day mechanical properties at 20°C./68° F. in accordance with test standards ASTM D7012-14e1 and ASTMD3967-16. 7-day mechanical properties included 7-day unconfinedcompressive strength (UCS), tensile strength (TS), Young's modulus (YM),TS/YM, and UCS/YM. The results in FIGS. 4A-4E demonstrated that Blends1-3 (without accelerator and with accelerator) could develop suitable7-day mechanical properties (e.g., a UCS greater than 700 psi, a TSgreater than 100 psi, and a YM greater than 3 GPa) with and withoutaccelerator. Based on these results, Blend 2 (without accelerator andwith accelerator) was optimum among Blends 1-3 (without accelerator andwith accelerator).

Example 2

Cement blends 4-9 were prepared according to compositions in Table 2.Compositions were prepared per API procedures with each of the cementblends by mixing the cement blend with water, with and/or without a salt(sodium sulfate and/or sodium chloride), and were named “Blend x(without accelerator)” and “Blend x (with accelerator)”, respectively,wherein x is the number of the cement blend. The wt. % is the weightpercentage of a component in a cement blend. Blends 6 (withoutaccelerator), 8 (without accelerator), and 9 (without accelerator) hadthe same cement blend with different densities.

TABLE 2 Cement blend composition Blend 4 Blend 5 Blend 6 Blend 7 Blend 8Blend 9 Cement Without With Without With Without With Without WithWithout Without blend Unit accelerator accelerator acceleratoraccelerator accelerator accelerator accelerator accelerator acceleratoraccelerator Cementitious wt. % 45 45 45 45 45 45 45 45 45 45 materialAplite wt. % 50 50 35 35 25 25 15 15 25 25 Pozzolanic wt. % 0 0 15 15 2525 35 35 25 25 material Silica fume wt. % 5 5 5 5 5 5 5 5 5 5Accelerator % BWOB — 1 — 1 — 1 — 1 — — Density kg/m³ 1,700 1,700 1,7001,700 1,700 1,700 1,700 1,700 1,800 1,900

24-hour crush compressive strength of Blends 4-7 (without acceleratorand with accelerator) were measured at different temperatures inaccordance with test standard API-RP-10B-2. Results in FIGS. 5A and 5Bshows that the 24-hour crush compressive strength increased as thetemperature increased for the same blend, 24-hour crush compressivestrength increased as the pozzolanic material content increased, and forthe same blend and temperature the composition with accelerator had agreater 24-hour crush compressive strength than the composition withoutaccelerator.

28-day permeability of Blends 4-7 (without accelerator) at 80° C./176°F. and 150° C./302° F. was measured in a Hassler type core holder inaccordance with test standard API-RP-10B-2. Results in FIG. 5C showsthat at 80° C./176° F. all the samples had a 28-day permeability equalto or lower than 0.01 μD, at 150° C./302° F. Blends 6-7 (withoutaccelerator) had a 28-day permeability equal to or lower than 4 μD.

A ring expansion test was conducted at 80° C./176° F. for Blend 6(without accelerator) with no expansion additive (EA), 2% EA, and 4% EABWOB according to the procedures as in Example 1. For comparison, basicclass G cement based samples with no EA and 4% EA mixed at 1.70 specificgravity were tested in parallel. FIGS. 5D and 5E show the 14-day ringexpansion test results. After 14 days from preparation, thecircumferential change of Blend 6 (without accelerator) with no EA, 2%EA, and 4% EA were from about 0.12% to about 0.34%. Increasing the EAamount in Blend 6 (without accelerator) increased the circumferentialchange. Basic class G cement based samples had no circumferentialincrease (reduction was not measured) with no EA. Blend 6 (withoutaccelerator) with no EA, 2% EA, and 4% EA had greater expansion than thecorresponding basic class G cement based samples at the sametemperature.

FIG. 5F shows the ring expansion test results of Blend 6 (withoutaccelerator) with no EA at 176° F. for a longer term. On day 28, thetemperature was increased to 150° C./302° F. and the circumferentialchange was from about 0.12% to about 0.14%.

Similar as Example 1, experiments and calculations were performed toBlends 4-7 (without accelerator) for 7-day mechanical properties at 80°C./176° F. and 150° C./302° F. in accordance with ASTM D7012-14e1 andASTM D3967-16. The results in FIGS. 6A-6E demonstrated that Blends 4-7(without accelerator) could develop suitable 7-day mechanical properties(e.g., a UCS greater than 700 psi, a TS greater than 100 psi, and a YMgreater than 3 GPa) at the two temperatures. As the temperatureincreased, compressive strength, tensile strength, and Young's modulusincreased. Based on these results, Blend 6 (without accelerator) wasoptimum among Blends 4-7 (without accelerator).

Example 3

Yield corrected carbon footprint was calculated for Blend 6 (withoutaccelerator), Blend 8 (without accelerator), and Blend 9 (withoutaccelerator) in Table 2, as well as for a class G cement based sample(specific gravity or SG=1.90) and a silica based sample (SG=1.90). Theresults are shown in FIG. 7 . The term “yield correction” means that thecarbon footprint of the blend has been used in combination with theyield factor of the subject slurry design to calculate the carbonfootprint per m³ volume of the cement slurry, for comparison purpose, asthe blend CO₂ footprint in itself is not a suitable comparison.

According to the results of Blends 6 (without accelerator), 8 (withoutaccelerator), and 9 (without accelerator) in FIG. 7 , lower density (orSG) of a cement slurry generally increased the yield factor and thusreduced the yield corrected carbon footprint for the same blend.Therefore, lower the density (or SG) of a cement slurry can lower theyield corrected carbon footprint while meeting design criteria.

Example 4

Ultrasonic cement analyzer (UCA) test was conducted to measurecompressive strength after preparation of cement slurry samples. FIG. 8shows a UCA chart of a class G cement based sample (SG=1.70) at 150°C./302° F., where the compressive strength decreased as time increased(i.e., strength retrogression) from the 2nd day of the experiment. Sonicstrength is a measure of compressive strength based on “transit time” ofsoundwaves through the cement. The sonic strength is an indicator ofcrush compressive strength and is often used to monitor compressivestrength versus time. FIG. 9A shows an 83-day UCA chart of Blend 6(without accelerator) at the same condition without strengthretrogression. FIG. 9B shows a 62-day UCA chart of Blend 6 (withoutaccelerator) at 180° C./356° F. without strength retrogression. Thisdemonstrates that at 150° C./302° F. and 180° C./356° F., strengthretrogression can be avoided for Blend 6 (without accelerator).

ADDITIONAL DISCLOSURE

The following is provided as additional disclosure for combinations offeatures and embodiments of the present disclosure.

A first embodiment, which is a composition comprising a cementitiousmaterial, a pozzolanic material, aplite, and an aqueous fluid.

A second embodiment, which is the composition of the first embodiment,wherein the cementitious material comprises a Portland cement.

A third embodiment, which is the composition of the first embodiment,wherein the pozzolanic material comprises a material selected from thegroup consisting of Trass flour, recycled glass, fly ash, bottom ash,cenospheres, glass bubbles, slag, clays, calcined clays, partiallycalcined clays, kaolinite clays, lateritic clays, illite clays,crystalline silica, silica flour, cement kiln dust, volcanic rock,natural pozzolans, mine tailings, diatomaceous earth, zeolite, shale,ground vitrified pipe, agricultural waste ash, ground granulated blastfurnace slag, bentonite, pumice, and any combination thereof.

A fourth embodiment, which is the composition of the second embodiment,wherein the pozzolanic material comprises a material selected from thegroup consisting of Trass flour, recycled glass, fly ash, bottom ash,cenospheres, glass bubbles, slag, clays, calcined clays, partiallycalcined clays, kaolinite clays, lateritic clays, illite clays,crystalline silica, silica flour, cement kiln dust, volcanic rock,natural pozzolans, mine tailings, diatomaceous earth, zeolite, shale,ground vitrified pipe, agricultural waste ash, ground granulated blastfurnace slag, bentonite, pumice, and any combination thereof.

A fifth embodiment, which is the composition of the first embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises Trass flour.

A sixth embodiment, which is the composition of the second embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises Trass flour.

A seventh embodiment, which is the composition of the second embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises pumice.

An eighth embodiment, which is the composition of the second embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises calcined clay.

A ninth embodiment, which is the composition of the second embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises ground granulated blast furnace slag.

A tenth embodiment, which is the composition of the second embodiment,wherein the aplite comprises granite and the pozzolanic materialcomprises fly ash.

An eleventh embodiment, which is the composition of the secondembodiment, wherein the aplite comprises granite and the pozzolanicmaterial comprises bentonite.

A twelfth embodiment, which is the composition of the first embodiment,further comprising silica fume.

A thirteenth embodiment, which is the composition of the secondembodiment, further comprising silica fume.

A fourteenth embodiment, which is the composition of the fifthembodiment, further comprising silica fume.

A fifteenth embodiment, which is the composition of the sixthembodiment, further comprising silica fume.

A sixteenth embodiment, which is the composition of the firstembodiment, further comprising a sodium chloride and sodium sulfateblend.

A seventeenth embodiment, which is the composition of the secondembodiment, further comprising a sodium chloride and sodium sulfateblend.

An eighteenth embodiment, which is the composition of the fifthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A nineteenth embodiment, which is the composition of the sixthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A twentieth embodiment, which is the composition of the twelfthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A twenty-first embodiment, which is the composition of the thirteenthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A twenty-second embodiment, which is the composition of the fourteenthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A twenty-third embodiment, which is the composition of the fifteenthembodiment, further comprising a sodium chloride and sodium sulfateblend.

A twenty-fourth embodiment, which is the composition of any of the firstthrough the twenty-third embodiments, wherein: (i) the cementitiousmaterial is present in the composition in an amount ranging from about 1to about 90 weight percent by weight of blend (BWOB); (ii) thepozzolanic material is present in the composition in an amount rangingfrom about 1 to about 90 weight percent BWOB; (iii) the aplite ispresent in the composition in an amount ranging from about 1 to about 90weight percent BWOB; (iv) the silica fume is present in the compositionin an amount ranging from about 0.5 to about 50 weight percent BWOB; (v)the sodium chloride is present in the composition in an amount rangingfrom about 0.01 to about 10 weight percent BWOB; (vi) the sodium sulfateis present in the composition in an amount ranging from about 0.01 toabout 10 weight percent BWOB; and (vii) the aqueous fluid is present inan amount effective to form a pumpable slurry of the composition.

A twenty-fifth embodiment, which is the composition of any of the firstthrough the twenty-fourth embodiments, excluding an expansion additive.

A twenty-sixth embodiment, which is a composition comprising: (i)Portland cement in an amount ranging from about 1 to about 90 weightpercent BWOB; (ii) Trass flour in an amount ranging from about 1 toabout 90 weight percent BWOB; (iii) granite in an amount ranging fromabout 1 to about 90 weight percent BWOB; and (iv) aqueous fluid in anamount effective to form a pumpable slurry of the composition.

A twenty-seventh embodiment, which is the composition of thetwenty-sixth embodiment, further comprising (v) silica fume in an amountranging from about 0.5 to about 50 weight percent BWOB.

A twenty-eighth embodiment, which is the composition of the twenty-sixthor the twenty-seventh embodiment, further comprising (vi) sodiumchloride in an amount ranging from about 0.01 to about 10 weight percentBWOB; and (vii) sodium sulfate is present in the composition in anamount ranging from about 0.1 to about 10 weight percent BWOB.

A twenty-ninth embodiment, which is a method of servicing a wellborepenetrating a subterranean formation, comprising: placing a compositionof claim 1 into the wellbore; and allowing the composition to form a setcement.

A thirtieth embodiment, which is the method of the twenty-ninthembodiment, wherein the set cement has a positive expansion.

A thirty-first embodiment, which is the method of the twenty-ninth orthe thirtieth embodiment, wherein the set cement has a permeability offrom about 0.01 micro Darcy (μD) to about 30 μD.

A thirty-second embodiment, which is the composition of any of the thirdthrough the thirty-first embodiments, wherein the Trass flour has a d50particle size distribution of equal to or less than about 50 microns.

A thirty-third embodiment, which is the composition of any of the firstthrough the thirty-second embodiments, further comprising a pre-blendedstabilizing agent.

A thirty-fourth embodiment, which is the composition of the thirty-thirdembodiment, wherein the pre-blended stabilizing agent comprisesbentonite, sepiolite, attapulgite, water swellable synthetic clays,Diutan gum, xanthan gum, wellan gum, guar gum, modified guar gum,hydroxy ethyl cellulose, modified cellulose, other classes ofpolysaccharides, or combinations thereof.

A thirty-fifth embodiment, which is the composition of the thirty-thirdor the thirty-fourth embodiment, wherein the pre-blended stabilizingagent are present in the composition in an amount of from about 0.01%BWOB to about 10% BWOB.

A thirty-sixth embodiment, which is the composition of any of the firstthrough the thirty-fifth embodiments, further comprising one or moreadditives.

A thirty-seventh embodiment, which is the composition of thethirty-sixth embodiment, wherein the one or more additives compriseweighting agents, retarders, accelerators, activators, gas migrationcontrol additives, lightweight additives, gas-generating additives,mechanical-property-enhancing additives (e.g., carbon fibers, glassfibers, metal fibers, minerals fibers, polymeric elastomers, latexes,etc.), lost-circulation materials, filtration-control additives,fluid-loss-control additives, defoaming agents, foaming agents,transition time modifiers, dispersants, thixotropic additives,suspending agents, or combinations thereof.

A thirty-eighth embodiment, which is the composition of the thirty-sixthor the thirty-seventh embodiment, wherein the one or more additives arepresent in the composition in an amount of from about 0.01% BWOB toabout 50% BWOB based on the total weight of the cement blend.

A thirty-ninth embodiment, which is a method of preparing a compositionof any of the first through the thirty-eighth embodiments, comprising:mixing components of the composition using mixing equipment.

A fortieth embodiment, which is the method of any of the twenty-ninththrough the thirty-first embodiments, further comprising circulating thecomposition down through a conduit and back up through an annular spacebetween an outside wall of the conduit and a wall of the wellbore.

A forty-first embodiment, which is the method of any of the twenty-ninththrough the thirty-first embodiments, further comprising circulating thecomposition down through an annular space between an outside wall of aconduit and a wall of the wellbore and back up through the conduit.

A forty-second embodiment, which is a method of servicing a wellborewith a conduit disposed therein to form an annular space between awellbore wall and an outer surface of the conduit, comprising: placing acomposition of any of the first through the thirty-eighth embodimentsinto at least a portion of the annular space, and allowing at least aportion of the composition to set.

A forty-third embodiment, which is the method of the forty-secondembodiment, wherein placing the composition into at least a portion ofthe annular space comprises: circulating the composition down throughthe conduit and back up through the annular space.

A forty-fourth embodiment, which is method of the forty-secondembodiment, wherein placing the composition into at least a portion ofthe annular space comprises; circulating the composition down throughthe annular space and back up through the conduit.

A forty-fifth embodiment, which is the method of any of the forty-secondthrough the forty-fourth embodiments, wherein the conduit comprisescasing.

A forty-sixth embodiment, which is the composition of any of the firstthrough the forty-fifth embodiments, having a density of from about 500kg/m³ to about 3,000 kg/m³.

A forty-seventh embodiment, which is the composition of any of the firstthrough the forty-sixth embodiments, having a 7-day circumferentialchange in a range of from about 0.01% to about 2% at from about 20°C./68° F. to about 150° C./302° F., when measured in a ring expansiontest in accordance with test standard API 10B-5.

A forty-eighth embodiment, which is the composition of any of the firstthrough the forty-seventh embodiments, having a 14-day circumferentialchange in a range of from about 0.01% to about 2% at from about 20°C./68° F. to about 150° C./302° F., when measured in a ring expansiontest in accordance with test standard API 10B-5.

A forty-ninth embodiment, which is the composition of any of the firstthrough the forty-eighth embodiments, having a thickening time to reachabout 50 Bearden units of consistency (Bc) in a range of from about 2hours to about 20 hours at about 10° C./50° F., when measured inaccordance with test standard API-RP-10B-2.

A fiftieth embodiment, which is the composition of any of the firstthrough the forty-ninth embodiments, having a thickening time to reachabout 50 Bc in a range of from about 2 hours to about 20 hours at about20° C./68° F., when measured in accordance with test standardAPI-RP-10B-2.

A fifty-first embodiment, which is the composition of any of the firstthrough the fiftieth embodiments, having an increasing compressivestrength as time increases from about 1 week to about 6 weeks, at atemperature about 80° C./176° F. to about 180° C./356° F. in anultrasonic cement analyzer (UCA) test when measured in accordance withtest standard API-RP-10B-2.

A fifty-second embodiment, which is the composition of any of the firstthrough the fifty-first embodiments, having a 28-day permeability ofequal to or less than about 30 μD at from about 20° C./68° F. to about80° C./176° F. when measured in accordance with test standardAPI-RP-10B-2.

A fifty-third embodiment, which is the composition of any of the firstthrough the fifty-second embodiments, having a 28-day permeability ofequal to or less than about 30 μD at from about 80° C./176° F. to about150° C./302° F. when measured in accordance with test standardAPI-RP-10B-2.

A fifty-fourth embodiment, which is the composition of any of the firstthrough the fifty-third embodiments, having a 7-day unconfinedcompressive strength (UCS) of from about 200 psi to about 5,000 psi atfrom about 20° C./68° F. to about 150° C./302° F. when measured inaccordance with test standard ASTM D7012-14e1.

A fifty-fifth embodiment, which is the composition of any of the firstthrough the fifty-fourth embodiments, having a 7-day tensile strength(TS) of from about 25 psi to about 1,000 psi at from about 20° C./68° F.to about 150° C./302° F. when measured in accordance with test standardASTM D3967-16.

A fifty-sixth embodiment, which is the composition of any of the firstthrough the fifty-fifth embodiments, having a 7-day Young's modulus (YM)of from about 2 GPa to about 14 GPa at from about 20° C./68° F. to about150° C./302° F.

A fifty-seventh embodiment, which is the composition of any of the firstthrough the fifty-sixth embodiments, having a time to reach 50 psicompressive strength in a range of from about 2 hours to about 24 hoursat from about 20° C./68° F. to about 150° C./302° F. in an ultrasoniccement analyzer (UCA) test, when measured in accordance with teststandard API-RP-10B-2.

A fifty-eighth embodiment, which is the composition of any of the firstthrough the fifty-seventh embodiments, having a 24-hour compressivestrength in a range of from about 50 psi to about 10,000 psi at fromabout 10° C./50° F. to about 80° C./176° F. in a UCA test when measuredin accordance with test standard API-RP-10B-2.

A fifty-ninth embodiment, which is the composition of any of the firstthrough the fifty-eighth embodiments, having a 28-day compressivestrength in a range of from about 50 psi to about 10,000 psi at about80° C./176° F. to about 150° C./302° F. in a UCA test when measured inaccordance with test standard API-RP-10B-2.

A sixtieth embodiment, which is the composition of any of the firstthrough the fifty-ninth embodiments, having a yield corrected carbonfootprint of equal to or less than about 800 kilograms of equivalent CO₂per cubic meter of the composition (kg/m³).

A sixty-first embodiment, which is the composition of any of the firstthrough the sixtieth embodiments, being capable to withstand atemperature from about 0° C./32° F. to about 204° C./400° F.

While embodiments of the disclosure have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the disclosure. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the disclosuredisclosed herein are possible and are within the scope of thedisclosure. Where numerical ranges or limitations are expressly stated,such express ranges or limitations should be understood to includeiterative ranges or limitations of like magnitude falling within theexpressly stated ranges or limitations (e.g., from about 1 to about 10includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13,etc.). For example, whenever a numerical range with a lower limit,R_(L), and an upper limit, R_(U), is disclosed, any number fallingwithin the range is specifically disclosed. In particular, the followingnumbers within the range are specifically disclosed:R=R_(L)+k*(R_(U)−R_(L)), wherein k is a variable ranging from 1 percentto 100 percent with a 1 percent increment, i.e., k is 1 percent, 2percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98percent, 99 percent, or 100 percent. Moreover, any numerical rangedefined by two R numbers as defined in the above is also specificallydisclosed. When a feature is described as “optional,” both embodimentswith this feature and embodiments without this feature are disclosed.Similarly, the present disclosure contemplates embodiments where thisfeature is required and embodiments where this feature is specificallyexcluded. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments of the present disclosure.

What is claimed is:
 1. A composition comprising (i) a blend comprising a cementitious material, a pozzolanic material, aplite, and (ii) an aqueous fluid, wherein the composition has a positive expansion upon setting, wherein the cementitious material comprises a Portland cement, wherein the pozzolanic material comprises Trass flour, pumice, calcined clay, ground granulated blast furnace slag, fly ash, or bentonite, and wherein the aplite is present in the composition in an amount from about 15% by weight of the blend (BWOB) to about 35% BWOB.
 2. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises Trass flour.
 3. The composition of claim 2, wherein the blend further comprises silica fume.
 4. The composition of claim 3, further comprising a sodium chloride and sodium sulfate blend.
 5. The composition of claim 2, further comprising a sodium chloride and sodium sulfate blend.
 6. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises pumice.
 7. The composition of claim 6, wherein the blend further comprises silica fume.
 8. The composition of claim 7, further comprising a sodium chloride and sodium sulfate blend.
 9. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises calcined clay.
 10. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises ground granulated blast furnace slag.
 11. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises fly ash.
 12. The composition of claim 1, wherein the aplite comprises granite and the pozzolanic material comprises bentonite.
 13. The composition of claim 1, wherein the blend further comprises silica fume.
 14. The composition of claim 1, further comprising a sodium chloride and sodium sulfate blend.
 15. The composition of claim 1, further comprising a sodium chloride and sodium sulfate blend.
 16. A method of servicing a wellbore penetrating a subterranean formation, comprising: placing a composition of claim 1 into the wellbore; and allowing the composition to form a set cement.
 17. A composition comprising (i) a blend comprising a cementitious material, a pozzolanic material, aplite, and (ii) an aqueous fluid, wherein the composition has a positive expansion upon setting, wherein the cementitious material comprises a Portland cement, wherein the pozzolanic material comprises Trass flour, pumice, calcined clay, ground granulated blast furnace, fly ash, or bentonite, and wherein the aplite is present in the composition in an amount from about 15% BWOB to about 35% BWOB.
 18. The composition of claim 17, wherein the composition further comprises silica fume.
 19. The composition of claim 18, wherein the composition further comprises a sodium chloride and sodium sulfate blend.
 20. The composition of claim 19, wherein the pozzolanic material comprises Trass flour.
 21. The composition of claim 18, wherein the pozzolanic material comprises Trass flour.
 22. The composition of claim 18, wherein the pozzolanic material comprises fly ash.
 23. The composition of claim 17, wherein the composition further comprises a sodium chloride and sodium sulfate blend.
 24. A method of servicing a wellbore penetrating a subterranean formation, comprising: placing a composition of claim 17 into the wellbore; and allowing the composition to form a set cement. 